Method for operating a materials handling vehicle utilizing multiple detection zones

ABSTRACT

A multiple detection zone supplemental remote control system for a materials handling vehicle comprises one or more sensors capable of defining multiple contactless detection zones at least towards the front of the forward travel direction of a remotely controlled vehicle. The vehicle responds to the detection of objects within the designated zones based upon predetermined actions, such as to slow down or stop the vehicle, and/or to take other action, such as to perform a steer angle correction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/631,007, filed Dec. 4, 2009, entitled “MULTIPLE ZONE SENSING FORMATERIALS HANDLING VEHICLES,” which claims the benefit of each of U.S.Provisional Patent Application Ser. No. 61/119,952, filed Dec. 4, 2008,entitled “MULTIPLE ZONE SENSING FOR REMOTELY CONTROLLED MATERIALSHANDLING VEHICLE;” U.S. Provisional Patent Application Ser. No.61/222,632, filed Jul. 2, 2009, entitled “APPARATUS FOR REMOTELYCONTROLLING A MATERIALS HANDLING VEHICLE;” and U.S. Provisional PatentApplication Ser. No. 61/234,866, filed Aug. 18, 2009, entitled “STEERCORRECTION FOR A REMOTELY OPERATED MATERIALS HANDLING VEHICLE;” theentire disclosures of each of which are hereby incorporated by referenceherein. U.S. patent application Ser. No. 12/631,007 is aContinuation-In-Part of U.S. patent application Ser. No. 11/855,310,filed Sep. 14, 2007, entitled “SYSTEMS AND METHODS OF REMOTELYCONTROLLING A MATERIALS HANDLING VEHICLE; and U.S. patent applicationSer. No. 11/855,324, filed Sep. 14, 2007, entitled “SYSTEMS AND METHODSOF REMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE (now U.S. Pat. No.8,072,309); the entireties of both of which are hereby incorporated byreference herein and both of which claim the benefit of U.S. ProvisionalPatent Application Ser. No. 60/825,688, filed Sep. 14, 2006, entitled“SYSTEMS AND METHODS OF REMOTELY CONTROLLING A MATERIALS HANDLINGVEHICLE.” U.S. patent application Ser. No. 12/631,007 is related toInternational Application No. PCT/US09/66789, filed Dec. 4, 2009,entitled “MULTIPLE ZONE SENSING FOR MATERIALS HANDLING VEHICLES,” theentire disclosure of which is hereby incorporated by reference herein.This application is related to U.S. patent application Ser. Nos. ______and ______, which are each being filed concurrently with the presentapplication, are incorporated by reference herein, and are respectivelyentitled “MULTIPLE ZONE SENSING FOR MATERIALS HANDLING VEHICLESTRAVELING UNDER REMOTE CONTROL” and “MULTIPLE DETECTION ZONESUPPLEMENTAL REMOTE CONTROL SYSTEM FOR A MATERIALS HANDLING VEHICLE” andhave respective docket numbers CRN 415 V2A and CRN 415 V2A2.

BACKGROUND OF THE INVENTION

The present invention relates in general to materials handling vehicles,and more particularly, to systems and methods that integrate detectionzone information into supplemental wireless remote control arrangementsfor materials handling vehicles.

Low level order picking trucks are commonly used for picking stock inwarehouses and distribution centers. Such order picking trucks typicallyinclude load carrying forks and a power unit having a platform uponwhich an operator may step and ride while controlling the truck. Thepower unit also has a steerable wheel and corresponding traction andsteering control mechanisms, e.g., a movable steering arm that iscoupled to the steerable wheel. A control handle attached to thesteering arm typically includes the operational controls necessary fordriving the truck and operating its load handling features.

In a typical stock picking operation, an operator fills orders fromavailable stock items that are located in storage areas provided along aplurality of aisles of a warehouse or distribution center. In thisregard, the operator drives a low lever order picking truck to a firstlocation where item(s) are to be picked. In a pick process, the operatortypically steps off the truck, walks over to the appropriate locationand retrieves the ordered stock item(s) from their associated storagearea(s). The operator then places the picked stock on a pallet,collection cage or other support structure carried by the forks of theorder picking truck. Upon completing the pick process, the operatoradvances the order picking truck to the next location where item(s) areto be picked. The above process is repeated until all stock items on theorder have been picked.

It is not uncommon for an operator to repeat the pick process severalhundred times per order. Moreover, the operator may be required to picknumerous orders per shift. As such, the operator may be required tospend a considerable amount of time relocating and repositioning theorder picking truck, which reduces the time available for the operatorto spend picking stock.

BRIEF SUMMARY OF THE INVENTION

According to various aspects of the present invention, a materialshandling vehicle having detection zone control comprises a power unitfor driving the vehicle, a load handling assembly that extends from thepower unit, at least one contactless obstacle sensor on the vehicle anda controller. The obstacle sensor(s) are operable to define at least twodetection zones, each detection zone defining an area at least partiallyin front of a forward traveling direction of the vehicle. Moreover, thecontroller is configured to control at least one aspect of the vehicleand is further configured to receive information obtained from theobstacle sensor(s) and to perform a first action if the vehicle istraveling and an obstacle is detected in a first one of the detectionzones; and to perform a second action different from the first action ifthe vehicle is traveling and an obstacle is detected in a second one ofthe detection zones.

According to still further aspects of the present invention, a multipledetection zone control system for a materials handling vehicle comprisesat least one contactless obstacle sensor and a controller. The obstaclesensor(s) are operable to define at least two detection zones, eachdetection zone defining an area at least partially in front of a forwardtraveling direction of the vehicle when the vehicle is traveling. Thecontroller is configured to integrate with and control at least oneaspect of the vehicle. Additionally, the controller is furtherconfigured to receive information obtained from the obstacle sensor(s)to perform a first action if the vehicle is traveling and an obstacle isdetected in a first one of the detection zones and perform a secondaction different from the first action if the vehicle is traveling andan obstacle is detected in a second one of the detection zones.

According to various further aspects of the present invention, amaterials handling vehicle capable of supplemental remote control mayinclude detection zone control. The materials handling vehicle comprisesa power unit for driving the vehicle, a load handling assembly thatextends from the power unit and a receiver at the vehicle for receivingtransmissions from a corresponding remote control device. Thetransmissions from the remote control device to the receiver include atleast a first type signal designating a travel request, which requeststhe vehicle to travel by a predetermined amount. The vehicle alsoincludes at least one contactless obstacle sensor on the vehicle that isoperable to define at least two detection zones, each detection zonedefining an area at least partially in front of a forward travelingdirection of the vehicle when the vehicle is traveling under remotecontrol in response to a travel request.

Still further, the vehicle includes a controller that communicates withthe receiver and with a traction control system of the vehicle tooperate the vehicle under remote control in response to receiving travelrequests from the remote control device. The controller is configured toperform a first action if the vehicle is traveling under remote controlin response to a travel request and an obstacle is detected in a firstone of the detection zones and the controller is configured to perform asecond action different from the first action if the vehicle istraveling under remote control in response to a travel request and anobstacle is detected in a second one of the detection zones.

According to still further aspects of the present invention, systems andmethods are provided to implement a multiple detection zone supplementalremote control system, e.g., which can be installed on a materialshandling vehicle. The multiple detection zone supplemental remotecontrol system comprises a remote control device manually operable by anoperator to wirelessly transmit at least a first type signal designatinga travel request, which requests the vehicle to travel by apredetermined amount. The system also includes a receiver forinstallation on the vehicle that receives transmissions from thecorresponding remote control device. Still further, the system includesat least one contactless obstacle sensor that is operable to define atleast two detection zones, each detection zone defining an area at leastpartially in front of a forward traveling direction of the vehicle whenthe vehicle is traveling under remote control in response to a travelrequest.

The system also includes a controller that communicates with thereceiver and with a traction control system of the vehicle to operatethe vehicle under remote control in response to receiving travelrequests from the remote control device. The controller is configured toperform a first action if the vehicle is traveling under remote controlin response to a travel request and an obstacle is detected in a firstone of the detection zones and the controller is configured to perform asecond action different from the first action if the vehicle istraveling under remote control in response to a travel request and anobstacle is detected in a second one of the detection zones.

Still further, a method is provided for operating a materials handlingvehicle utilizing multiple detection zones. First and second detectionzones are defined in areas proximate to the vehicle. A first action isperformed if an unacceptable detection occurs in the first detectionzone, and a second action is performed different from the first actionif an unacceptable detection occurs in the second detection zone.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an illustration of a materials handling vehicle capable ofsupplemental remote control according to various aspects of the presentinvention;

FIG. 2 is a schematic diagram of several components of a materialshandling vehicle capable of supplemental remote control according tovarious aspects of the present invention;

FIG. 3 is a schematic diagram illustrating detection zones of amaterials handling vehicle according to various aspects of the presentinvention;

FIG. 4 is a schematic diagram illustrating an exemplary approach fordetecting an object according to various aspects of the presentinvention;

FIG. 5 is a schematic diagram illustrating a plurality of detectionzones of a materials handling vehicle according to further aspects ofthe present invention;

FIG. 6 is a schematic diagram illustrating a materials handling vehicleoperating under supplemental remote control in a warehouse aisleaccording to various aspects of the present invention;

FIG. 7 is a schematic diagram illustrating a plurality of detectionzones of a materials handling vehicle which are capable ofdistinguishing direction according to further aspects of the presentinvention;

FIGS. 8-10 illustrate the use of a plurality of detection zones toimplement a steering correction of a materials handling vehicle that isoperating under supplemental remote control according to various aspectsof the present invention;

FIG. 11 is a flow chart of a method of implementing steer correctionaccording to various aspects of the present invention; and

FIG. 12 is a schematic illustration of a materials handling vehicletraveling down a narrow warehouse aisle under remote wireless operation,which is automatically implementing a steer correction maneuveraccording to various aspects of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description of the illustrated embodiments,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration, and not by way oflimitation, specific embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand that changes may be made without departing from the spirit and scopeof various embodiments of the present invention.

Low Level Order Picking Truck:

Referring now to the drawings, and particularly to FIG. 1, a materialshandling vehicle, which is illustrated as a low level order pickingtruck 10, includes in general a load handling assembly 12 that extendsfrom a power unit 14. The load handling assembly 12 includes a pair offorks 16, each fork 16 having a load supporting wheel assembly 18. Theload handling assembly 12 may include other load handling features inaddition to, or in lieu of the illustrated arrangement of the forks 16,such as a load backrest, scissors-type elevating forks, outriggers orseparate height adjustable forks. Still further, the load handlingassembly 12 may include load handling features such as a mast, a loadplatform, collection cage or other support structure carried by theforks 16 or otherwise provided for handling a load supported and carriedby the truck 10.

The illustrated power unit 14 comprises a step-through operator'sstation dividing a first end section of the power unit 14 (opposite theforks 16) from a second end section (proximate the forks 16). Thestep-through operator's station provides a platform upon which anoperator may stand to drive the truck 10. The platform also provides aposition from which the operator may operate the load handling featuresof the truck 10. Presence sensors 58 may be provided, e.g., on, above,or under the platform floor of the operator's station. Still further,presence sensors 58 may be otherwise provided about the operator'sstation to detect the presence of an operator on the truck 10. In theexemplary truck of FIG. 1, the presence sensors 58 are shown in dashedlines indicating that they are positioned under the platform floor.Under this arrangement, the presence sensors 58 may comprise loadsensors, switches, etc. As an alternative, the presence sensors 58 maybe implemented above the platform 56, such as by using ultrasonic,capacitive or other suitable sensing technology.

An antenna 66 extends vertically from the power unit 14 and is providedfor receiving control signals from a corresponding remote control device70. The remote control device 70 may comprise a transmitter that is wornor otherwise maintained by the operator. As an example, the remotecontrol device 70 may be manually operable by an operator, e.g., bypressing a button or other control, to cause the device 70 to wirelesslytransmit at least a first type signal designating a travel request tothe vehicle, thus requesting the vehicle to travel by a predeterminedamount.

The truck 10 also comprises one or more obstacle sensors 76, which areprovided about the vehicle, e.g., towards the first end section of thepower unit 14 and/or to the sides of the power unit 14. The obstaclesensors 76 include at least one contactless obstacle sensor on thevehicle, and are operable to define at least two detection zones, eachdetection zone defining an area at least partially in front of a forwardtraveling direction of the vehicle when the vehicle is traveling underremote control in response to a travel request as will be described ingreater detail herein. The obstacle sensors 76 may comprise any suitableproximity detection technology, such as an ultrasonic sensors, opticalrecognition devices, infrared sensors, laser sensors, etc., which arecapable of detecting the presence of objects/obstacles within thepredefined detection zones of the power unit 14.

In practice, the truck 10 may be implemented in other formats, stylesand features, such as an end control pallet truck that includes asteering tiller arm that is coupled to a tiller handle for steering thetruck. In this regard, the truck 10 may have similar or alternativecontrol arrangements to that shown in FIG. 1. Still further, the truck10, supplemental remote control system and/or components thereof, maycomprise any additional and/or alternative features, such as set out inU.S. Provisional Patent Application Ser. No. 60/825,688, filed Sep. 14,2006 entitled “SYSTEMS AND METHODS OF REMOTELY CONTROLLING A MATERIALSHANDLING VEHICLE”, U.S. patent application Ser. No. 11/855,310, entitled“SYSTEMS AND METHODS OF REMOTELY CONTROLLING A MATERIALS HANDLINGVEHICLE”, U.S. patent application Ser. No. 11/855,324, entitled “SYSTEMSAND METHODS OF REMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE”, U.S.Provisional Patent Application Ser. No. 61/222,632, filed Jul. 2, 2009entitled “APPARATUS FOR REMOTELY CONTROLLING A MATERIALS HANDLINGVEHICLE,” and U.S. Provisional Patent Application Ser. No. 61/234,866,filed Aug. 18, 2009 entitled “STEER CORRECTION FOR A REMOTELY OPERATEDMATERIALS HANDLING VEHICLE”.

Control System for Remote Control of a Low Level Order Picking Truck:

Referring to FIG. 2, a block diagram 100 illustrates a controlarrangement for integrating remote control commands with the truck 10.The antenna 66 is coupled to a receiver 102 for receiving commandsissued by the remote control device 70. The receiver 102 passes thereceived control signals to a controller 103, which implements theappropriate response to the received commands. The response may compriseone or more actions, or inaction, depending upon the logic that is beingimplemented. Positive actions may comprise controlling, adjusting orotherwise affecting one or more components of the truck 10. Thecontroller 103 may also receive information from other inputs 104, e.g.,from sources such as the presence sensors 58, the obstacle sensors 76,switches, encoders and other devices/features available to the truck 10to determine appropriate action in response to the received commandsfrom the remote control device 70. The sensors 58, 76, etc. may becoupled to the controller 103 via the inputs 104 or via a suitable trucknetwork, such as a control area network (CAN) bus 110.

In an exemplary arrangement, the remote control device 70 is operativeto wirelessly transmit a control signal that represents a first typesignal such as a travel command to the receiver 102 on the truck 10. Thetravel command is also referred to herein as a “travel signal”, “travelrequest” or “go signal”. The travel request is used to initiate arequest to the truck 10 to travel by a predetermined amount, e.g., tocause the truck 10 to advance or jog in a first direction by a limitedtravel distance. The first direction may be defined, for example, bymovement of the truck 10 in a power unit 14 first, i.e., forks 16 to theback, direction. However, other directions of travel may alternativelybe defined. Moreover, the truck 10 may be controlled to travel in agenerally straight direction or along a previously determined heading.Correspondingly, the limited travel distance may be specified by anapproximate travel distance, travel time or other measure.

Thus, a first type signal received by the receiver 102 is communicatedto the controller 103. If the controller 103 determines that the travelsignal is a valid travel signal and that the current vehicle conditionsare appropriate (explained in greater detail below), the controller 103sends a signal to the appropriate control configuration of theparticular truck 10 to advance and then stop the truck 10. As will bedescribed in greater detail herein, stopping the truck 10 may beimplemented, for example, by either allowing the truck 10 to coast to astop or by applying a brake to stop the truck.

As an example, the controller 103 may be communicably coupled to atraction control system, illustrated as a traction motor controller 106of the truck 10. The traction motor controller 106 is coupled to atraction motor 107 that drives at least one steered wheel 108 of thetruck 10. The controller 103 may communicate with the traction motorcontroller 106 so as to accelerate, decelerate, adjust and/or otherwiselimit the speed of the truck 10 in response to receiving a travelrequest from the remote control device 70. The controller 103 may alsobe communicably coupled to a steer controller 112, which is coupled to asteer motor 114 that steers at least one steered wheel 108 of the truck10. In this regard, the truck may be controlled by the controller 103 totravel a predetermined path or maintain a predetermined heading inresponse to receiving a travel request from the remote control device70.

As yet another illustrative example, the controller 103 may becommunicably coupled to a brake controller 116 that controls truckbrakes 117 to decelerate, stop or otherwise control the speed of thetruck in response to receiving a travel request from the remote controldevice 70. Still further, the controller 103 may be communicably coupledto other vehicle features, such as main contactors 118, and/or otheroutputs 119 associated with the truck 10, where applicable, to implementdesired actions in response to implementing remote travel functionality.

According to various aspects of the present invention, the controller103 may communicate with the receiver 102 and with the tractioncontroller 106 to operate the vehicle under remote control in responseto receiving travel commands from the associated remote control device70. Moreover, the controller 103 may be configured to perform a firstaction if the vehicle is traveling under remote control in response to atravel request and an obstacle is detected in a first one of thedetection zones. The controller 103 may be further configured to performa second action different from the first action if the vehicle istraveling under remote control in response to a travel request and anobstacle is detected in a second one of the detection zones. In thisregard, when a travel signal is received by the controller 103 from theremote control device 70, any number of factors may be considered by thecontroller 103 to determine whether the travel signal should be actedupon and what action(s) should be taken, if any. The particular vehiclefeatures, the state/condition of one or more vehicle features, vehicleenvironment, etc., may influence the manner in which controller 103responds to travel requests from the remote control device 70.

The controller 103 may also refuse to acknowledge the travel signaldepending upon vehicle condition(s), e.g., that relate to environmentalor/operational factor(s). For example, the controller 103 may disregardan otherwise valid travel request based upon information obtained fromone or more of the sensors 58, 76. For example, according to variousaspects of the present invention, the controller 103 may optionallyconsider factors such as whether an operator is on the truck 10 whendetermining whether to respond to a travel command from the remotecontrol device 70. For example, as noted above, the truck 10 maycomprise at least one presence sensor 58 for detecting whether anoperator is positioned on the vehicle. In this regard, the controller103 may be further configured to respond to a travel request to operatethe vehicle under remote control when the presence sensor(s) 58designate that no operator is on the vehicle.

Any other number of reasonable conditions may also/alternatively beimplemented by the controller 103 to interpret and take action inresponse to received signals. Other exemplary factors are set out ingreater detail in U.S. Provisional Patent Application Ser. No.60/825,688, filed Sep. 14, 2006 entitled “SYSTEMS AND METHODS OFREMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE”, U.S. patentapplication Ser. No. 11/855,310, entitled “SYSTEMS AND METHODS OFREMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE” and U.S. patentapplication Ser. No. 11/855,324, entitled “SYSTEMS AND METHODS OFREMOTELY CONTROLLING A MATERIALS HANDLING VEHICLE”, the disclosures ofwhich are each already incorporated by reference herein.

Upon acknowledgement of a travel request, the controller 103 interactswith the traction motor controller 106, e.g., directly, indirectly, viathe CAN bus 110, etc., to advance the truck 10. Depending upon theparticular implementation, the controller 103 may interact with thetraction motor controller 106 to advance the truck 10 by a predetermineddistance. Alternatively, the controller 103 may interact with thetraction motor controller 106 to advance the truck 10 for a period oftime in response to the detection and maintained actuation of a travelcontrol on the remote 70. Further alternatively, the truck 10 may beconfigured to jog for as long as a travel control signal is received.Still further alternatively, the controller 103 may be configured to“time out” and stop the travel of the truck 10 based upon apredetermined event, such as exceeding a predetermined time period ortravel distance regardless of the detection of maintained actuation of acorresponding control on the remote control device 70.

The remote control device 70 may also be operative to transmit a secondtype signal, such as a “stop signal”, designating that the truck 10should brake and/or otherwise come to rest. The second type signal mayalso be implied, e.g., after implementing a “travel” command, e.g.,after the truck 10 has traveled a predetermined distance, traveled for apredetermined time, etc., under remote control in response to the travelcommand. If the controller 103 determines that the signal is a stopsignal, the controller 103 sends a signal to the traction controller106, the brake controller 116 and/or other truck component to bring thetruck 10 to a rest. As an alternative to a stop signal, the second typesignal may comprise a “coast signal”, designating that the truck 10should coast, eventually slowing to rest.

The time that it takes to bring the truck 10 to a complete rest mayvary, depending for example, upon the intended application, theenvironmental conditions, the capabilities of the particular truck 10,the load on the truck 10 and other similar factors. For example, aftercompleting an appropriate jog movement, it may be desirable to allow thetruck 10 to “coast” some distance before coming to rest so that thetruck 10 stops slowly. This may be achieved by utilizing regenerativebraking to slow the truck 10 to a stop. Alternatively, a brakingoperation may be applied after a predetermined delay time to allow apredetermined range of additional travel to the truck 10 after theinitiation of the stop operation. It may also be desirable to bring thetruck 10 to a relatively quicker stop, e.g., if an object is detected inthe travel path of the truck 10 or if an immediate stop is desired aftera successful jog operation. For example, the controller may applypredetermined torque to the braking operation. Under such conditions,the controller 103 may instruct the brake controller 116 to apply thebrakes 117 to stop the truck 10.

Detection Zones of a Materials Handling Vehicle:

Referring to FIG. 3, according to various aspects of the presentinvention, one or more obstacle sensors 76 are configured so as tocollectively enable detection of objects/obstacles within multiple“detection zones”. In this regard, the controller 103 may be configuredto alter one or more operational parameter of the truck 10 in responseto detection of an obstacle in one or more of the detection zones as setout in greater detail herein. The control of the vehicle utilizingdetection zones may be implemented when an operator is riding/drivingthe vehicle. The control of the vehicle utilizing detection zones mayalso be integrated with supplemental remote control as set out anddescribed more fully herein.

Although six obstacle sensors 76 are shown for purposes of clarity ofdiscussion herein, any number of obstacle sensors 76 may be utilized.The number of obstacle sensors 76 will likely vary, depending upon thetechnology utilized to implement the sensor, the size and/or range ofthe detection zones, the number of detection zones, and/or otherfactors.

In the illustrative example, a first detection zone 78A is locatedproximate to the power unit 14 of the truck 10. A second detection zone78B is defined adjacent to the first detection zone 78A and appears togenerally circumscribe the first detection zone 78A. A third area isalso conceptually defined as all area outside the first and seconddetection zones 78A, 78B. Although the second detection zone 78B isillustrated as substantially circumscribing the first detection zone78A, any other practical arrangement that defines the first and seconddetection zones 78A, 78B may be realized. For example, all or certainportions of the detection zones 78A, 78B may intersect, overlap, or bemutual exclusive. Moreover, the particular shape of the detection zones78A, 78B can vary. Still further, any number of detection zones may bedefined, further examples of which are described in greater detailherein.

Still further, the detection zones need not surround the entire truck10. Rather, the shape of the detection zones may be dependent upon theparticular implementation as set out in greater detail herein. Forexample, if the detection zones 78A, 78B are to be used for speedcontrol while the truck 10 is moving without an operator riding thereon,such as under remote travel control in a power unit first (forks to therear) orientation, then the detection zones 78A, 78B may be orientedforward of the direction of travel of the truck 10. However, thedetection zones can also cover other areas, e.g., adjacent to the sidesof the truck 10.

According to various aspects of the present invention, the firstdetection zone 78A may further designate a “stop zone”. Correspondingly,the second detection zone 78B may further designate a “first speedzone”. Under this arrangement, if an object, e.g., some form ofobstacle, is detected within the first detection zone 78A, and thematerials handling vehicle 10 is traveling under remote control inresponse to a travel request, then the controller 103 may be configuredto implement an action such as a “stop action” to bring the truck 10 toa stop. In this regard, travel of the truck 10 may continue once theobstacle is clear, or a second, subsequent travel request from theremote control device 70 may be required to restart travel of the truck10.

If a travel request is received from the remote control device 70 whilethe truck is at rest and an object is detected within the firstdetection zone 78A, then the controller 103 may refuse the travelrequest and keep the truck at rest until the obstacle is cleared out ofthe stop zone.

If an object/obstacle is detected within the second detection zone 78B,and the materials handling vehicle 10 is traveling under remote controlin response to a travel request, then the controller 103 may beconfigured to implement a different action. For example, the controller103 may implement a first speed reduction action to reduce the speed ofthe vehicle to a first predetermined speed, such as where the vehicle istraveling at a speed greater than the first predetermined speed.

Thus, assume the truck 10 is traveling in response to implementing atravel request from the remote control device at a speed V2 asestablished by a set of operating conditions where the obstacle sensors76 do not detect an obstacle in any detection zone. If the truck isinitially at rest, the truck may be accelerated up to speed V2. Thedetection of an obstacle within the second detection zone 78B (but notthe first detection zone 78A) may cause the truck 10, e.g., via thecontroller 103 to alter at least one operational parameter, e.g., toslow down the truck 10 to a first predetermined speed V1, which isslower than the speed V2. That is, V1<V2. Once the obstacle is clearedfrom the second detection zone 78B, the truck 10 may resume its speedV2, or the truck 10 may maintain its speed V1 until the truck stops andthe remote control device 70 initiates another travel request. Stillfurther, if the detected object is subsequently detected within thefirst detection zone 78A, the truck 10 will be stopped as described morefully herein.

Assume as an illustrative example, that the truck 10 is configured totravel at a speed of approximately 2.5 miles per hour (mph) (4Kilometers per hour (Km/h)) if the truck 10 is traveling without anoperator and is under remote control in response to a travel requestfrom a corresponding remote control 70, so long as no object is detectedin a defined detection zone. If an obstacle is detected in the seconddetection zone 78B, then the controller 103 may adjust the speed of thetruck 10 to a speed of approximately 1.5 mph (2.4 Km/h) or some otherspeed less than 2.5 miles per hour (mph) (4 Kilometers per hour (Km/h)).If an obstacle is detected in the first detection zone 78A, then thecontroller 103 stops the truck 10.

The above example assumes that the truck 10 is traveling under remotecontrol without an operator. In this regard, the obstacle sensors 76 canbe used to adjust the operating conditions of the unoccupied truck 10.However, the obstacle sensors 76 and corresponding controller logic mayalso be operative when the truck 10 is being driven by an operator,e.g., riding on the platform or other suitable location of the truck 10.Thus, according to various aspects of the present invention, thecontroller 103 may stop the vehicle or refuse to allow the vehicle tomove if an object is detected within the stop zone 78A regardless ofwhether the truck is being driven by an operator or operating underremote control. Correspondingly, depending upon the specificimplementation, the speed control capability of the second detectionzone 78B may be implemented regardless of whether the vehicle isoperating unoccupied under remote control, or whether an operator isriding on the vehicle while driving it.

However, according to various aspects of the present invention, theremay be situations where it is desirable to disable one or more of thedetection zones when the truck 10 is being driven by an operator. Forexample, it may be desirable to override/disable the obstacle sensors76/controller logic while the operator is driving the truck 10regardless of external conditions. As a further example, it may bedesirable to override/disable the obstacle sensors 76/controller logicwhile the operator is driving the truck 10 to allow the operator tonavigate the truck 10 in tight quarters, e.g., to navigate tight spaces,travel around corners, etc., that might otherwise activate one or moreof the detection zones. As such, the activation of the controller logicto utilized the detection of objects in the detection zones to controlthe vehicle while the vehicle is occupied by an operator, according tovarious aspects of the present invention, may be manually controlled,programably controlled or otherwise selectively controlled.

Referring to FIG. 4, according to further aspects of the presentinvention, one or more of the obstacle sensors 76 may be implemented byultrasonic technology or other suitable contactless technology capableof a distance measurement and/or position determination. Thus, thedistance to an object can be measured, and/or a determination may bemade so as to ascertain whether the detected object is within adetection zone 78A, 78B, e.g., by virtue of the distance of the objectfrom the truck 10. As an example, an obstacle sensor 76 may beimplemented by an ultrasonic sensor that provides a “ping” signal, suchas a high frequency signal generated by a piezo element. The ultrasonicsensor 76 then rests and listens for a response. In this regard, time offlight information may be determined and utilized to define each zone.Thus, a controller, e.g., the controller 103 or a controllerspecifically associated with the obstacle sensors 76 may utilizesoftware that looks at time of flight information to determine whetheran object is within a detection zone.

According to further aspects of the present invention, multiple obstaclesensors 76 can work together to obtain object sensing. For example, afirst ultrasonic sensor may send out a ping signal. The first ultrasonicsensor and one or more additional ultrasonic sensors may then listen fora response. In this way, the controller may use diversity in identifyingthe existence of an object within one or more of the detection zones.

With reference to FIG. 5, an implementation of multiple speed zonecontrol is illustrated according to yet further aspects of the presentinvention. As illustrated, three detection zones are provided. If anobject such as an obstacle is detected in the first detection zone 78Aand the truck 10 is moving under remote control, then a first action maybe performed, e.g., the truck 10 may be brought to a stop as describedmore fully herein. If an object such as an obstacle is detected in thesecond detection zone 78B and the truck 10 is moving under remotecontrol, then a second action may be performed, e.g., the vehicle speedmay be limited, reduced, etc. Thus, the second detection zone 78B mayfurther designate a first speed zone. For example, the speed of thetruck 10 may be reduced and/or limited to a first relatively slow speed,e.g., approximately 1.5 mph (2.4 Km/h).

If an object such as an obstacle is detected in the third detection zone78C and the truck 10 is moving under remote control, then a third actionmay be performed, e.g., the truck 10 may be reduced in speed orotherwise limited to a second speed, e.g., approximately 2.5 mph (4Km/h). Thus, the third detection zone may further designate a secondspeed zone. If no obstacles are detected in the first, second and thirddetection zones 78A, 78B, 78C, then the vehicle may be remotelycontrolled to travel, e.g., in response to a remote travel request, at arate that is greater than the rate of speed when an obstacle is in thethird detection zone, e.g., a speed of approximately 4 mph (6.2 Km/h).

As FIG. 5 further illustrates, the detection zones may be defined bydifferent patterns relative to the truck 10. Also, in FIG. 5, a seventhobstacle sensor 76 is illustrated for purposes of illustration. By wayof illustration, the seventh obstacle sensor 76 may be approximatelycentered, such as on the bumper or other suitable location on the truck10. On an exemplary truck 10, the third zone 78C may extendapproximately 6.5 feet (2 meters) forward of the power unit 14 of thetruck 10.

According to various aspects of the present invention, any number ofdetection zones of any shape may be implemented. For example, dependingupon desired truck performance, many small zones may be defined atvarious coordinates relative to the truck 10. Similarly, a few largedetection zones may be defined based upon desired truck performance. Asan illustrative example, a table may be set up in the memory of thecontroller. If travel speed while operating under remote travel controlis an operational parameter of interest, then the table may associatetravel speed with the detection zones defined by distance, range,position coordinates or some other measure. If the truck 10 is travelingunder remote control and an obstacle sensor detects an object, then thedistance to that detected object may be used as a “key” to look up acorresponding travel speed in the table. The travel speed retrieved fromthe table can be utilized by the controller 103 to adjust the truck 10,e.g., to slow it down, etc.

Depending upon factors such as the desired speed of the truck whenoperating under remote control and the required stopping distance, theanticipated load to be transported by the truck 10, whether a certainamount of coast is required for load stability, vehicle reaction time,etc., the areas of each detection zone may be chosen. Moreover, factorssuch as the range of each desired detection zone etc. may be consideredto determine the number of obstacle sensors 76 required. In this regard,such information may be static, or dynamic, e.g., based upon operatorexperience, vehicle load, nature of the load, environmental conditions,etc.

As an illustrative example, in a configuration with multiple detectionzones, e.g., three detection zones, as many as seven or more objectdetectors, e.g., ultrasonic sensors, laser sensors, etc. may be requiredto provide a range of coverage desired by a corresponding application.In this regard, the detector(s) may be able to look ahead of thedirection of travel of the vehicle by a sufficient distance to allow theappropriate response, e.g., to slow down. In this regard, at least onesensor may be capable of looking several meters forward in the directionof travel of the truck 10.

According to various aspects of the present invention, the multipledetection speed zones allows a relatively greater maximum forward travelspeed while operating under remote control that prevents unnecessarilyearly vehicle stops by providing one or more intermediate zones wherethe vehicle slows down before deciding to come to a complete stop.

According to further aspects of the present invention, the utilizationof multiple detection zones allows a system that rewards thecorresponding operator for better alignment of the truck 10 during pickoperations. For example, referring to FIG. 6, an operator has positionedthe truck 10 so as to not be aligned with a warehouse aisle. As such, asthe vehicle is jogged forward, the second detection zone 78B mayinitially detect an obstacle such as a pick bin or warehouse rack. Inresponse to detecting the rack, the vehicle will slow down. If the rackis sensed in the first detection zone 78A, then the vehicle will come torest, even if the truck 10 has not jogged its entire programmed jogdistance. Similar unnecessary slow downs or stops may also occur incongested and/or messy aisles.

According to various aspects of the present invention, the truck 10 maymake decisions based upon the information obtained from the obstaclesensors 76. Moreover, the logic implemented by the truck 10 in responseto the detection zones may be changed or varied depending upon a desiredapplication. As a few illustrative examples, the boundaries of each zonein a multiple zone configuration may be programably (and/orreprogramably) entered in the controller, e.g., flash programmed. Inview of the defined zones, one or more operational parameters may beassociated with each zone. The established operational parameters maydefine a condition, e.g., maximum allowable travel speed, an action,e.g., brake, coast or otherwise come to a controlled stop, etc. Theaction may also be an avoidance action. For example, an action maycomprise adjusting a steer angle or heading of the truck 10.

Obstacle Avoidance

According to further aspects of the present invention, the detectionzones may be utilized to perform obstacle avoidance. As noted in greaterdetail herein, the controller may further communicate with a steercontroller of the vehicle. As such, one or more of the detection zonesmay be designated as steer angle correction zone(s). In this regard, thecontroller 103 may be further configured to implement a steer anglecorrection if an obstacle is detected in the steer angle correctionzone(s).

For example, when performing stock picking operations, a vehicleoperator may not position the vehicle on the exact heading necessary tojog down a warehouse aisle. Rather, the vehicle may be slightly skewedwith regard to the bins along the aisle edge. In that regard, thevehicle may have a heading that would cause the vehicle to steer into arack. Accordingly, the operational parameters adjusted when an obstacleis detected in a particular zone may include steer angle correction inaddition to, or in lieu of vehicle speed adjustment. Under thisarrangement, the vehicle may utilize a servo controlled steering system.The controller can integrate, communicate or otherwise alter the controlof the servo to change the steer heading of the truck 10.

When making steer angle corrections, it may be necessary for thecontroller to determine whether the steer correction should be made toturn the vehicle to the left or to the right. In this regard, theobstacle sensors 76 or some other additional/ancillary sensors areconfigured to communicate information to the controller 103 to enablethe controller 103 to make direction based decisions in response todetecting an object in a detection zone. As an illustrative example,where a plurality of obstacle sensors 76 are provided, the detectionzones may be bisected so that a detected object may be discerned, forexample, as being to the right or left of the truck 10.

For example, referring to FIG. 7, each detection zone is furthersubdivided into a left and right component. Although shown as twosubdivisions for purposes of illustration, any reasonable number ofsubdivisions may be utilized, depending upon the capability of theparticular obstacle sensors 76 that are utilized in an implementation.

Steer correction, e.g., to automatically align the truck 10 within awarehouse aisle, is a difficult task. If an under-correction is applied,or if the steer correction is not applied in a timely, appropriatemanner, the vehicle may not properly adjust the truck to an appropriateheading. Thus, operator involvement is required to straighten out thevehicle. This takes away picking time from the operator.

However, if the steer correction overcompensates the steer angle, it ispossible that the vehicle will “ping pong” back and forth down theaisle. This is also a potential waste of time for the picker. This pingpong affect may also cause congestion in crowded warehouse aisles.

Referring back to FIG. 2, the controller 103 may communicate, e.g., viathe CAN bus 110 or by other means, with a steer control system, e.g.,the steer controller 112, to cause the truck 10 to adjust a travel pathof the truck 10. For example, the controller 103 may communicate with asteer controller 112 to command or otherwise control a steer motor 114or other suitable control device, which also couples to the steeredwheel(s) 108 of the truck 10. The controller 103 may straighten out thetruck 10, or adjust a steer angle of the truck 10 before or during awireless remote control initiated travel operation. As such, thecontroller 103 may default to a mode of operation wherein the truck 10travels in a straight direction or along a predetermined heading whenthe truck 10 is moving under wireless remote control in response toreceipt of a travel request. The controller 103 may further impose asteer angle limit during remote control operations if the truck 10 is totravel in a direction where the steered wheel(s) 108 is not straight.For example, the controller 103 may limit the angle that the truck 10can travel when executing remote controlled travel requests to a rangeof approximately 5 to 10 degrees. Thus, in addition to jogging thetraction motor 107, the controller 103 may also straighten out orotherwise adjust or control the steered wheel 108.

According to various aspects of the present invention, detection zonesare utilized to implement steer angle compensation. In particular, afirst steer correction is associated with a first one of the zones,e.g., the outer-most zone. Where multiple zones are provided, multiplesteer angle corrections amounts can be associated with each zone.

As an illustrative example, as illustrated in FIG. 8, a truck 10 istraveling down a warehouse aisle along a heading that is directing thetruck towards a rack (not parallel to the aisle passageway. The truck 10is operating under remote control utilizing a plurality, e.g., threedetection zones. A first steer correction angle α1 is associated withthe outer-most zone (third detection zone in this example). A secondsteer correction angle α2 is associated with the adjacent zone (seconddetection zone in this example). In addition, a speed reduction may beassociated with the third detection zone, a different speed reductionmay be associated with the second detection zone and a stop zone may beassociated with the first detection zone.

Further, the steer angle correction may be different for each zone. Asillustrated, the rack has breached the third detection zone to the leftof the truck 10. In response thereto, the controller 103 causes thetruck 10 to implement a first steer correction α1. With reference toFIG. 9, the truck 10 has slowed down by virtue of entering zone 3. Thetruck 10 has also implemented a first steer angle correction α1.However, in this illustrative example, the controller detects the rackin the second detection zone, again, to the left of the truck 10. Inresponse thereto, the controller causes the truck to implement a steercorrection α2 associated with zone 2.

Referring to FIG. 10, upon implementing the steer angle correction, thetruck 10 is suitably positioned to travel down the warehouse aisle.

By way of illustration, and not by way of limitation, α1<α2. Thus, forexample, α1 may comprise a steer angle correction of approximately 2degrees, whereas α2 may comprise a steer angle correction ofapproximately 5 degrees. After the appropriate corrections of steerangle, the vehicle is adjusted to a heading that extends substantiallyparallel to the aisle passageway. The particular angles may varydepending upon a number of factors. Moreover, the steer angle may bestatically programmed, or the angle may dynamically vary, e.g.,depending upon one or more conditions.

According to aspects of the present invention, the steer correctionresults in the truck traveling down the warehouse aisle such that therack does not breach any of the detection zones. This allows the truck10 to travel under remote control at its maximum speed without incurringthe speed reduction that occurs when an object is detected within adetection zone.

In practice, the range of each obstacle sensor 76 may be different,depending upon the specific implementation and selection of proximitydetecting technology. For example, one or more of the obstacle sensors76 towards the front of the power unit 14 may have a range ofapproximately 0-5 feet (0-1.5 meters) or more and the obstacle sensors76 to the sides of the power unit 14 may have a range of approximately0-2 feet (0-0.6 meters). Moreover, the detection range of the obstaclesensors 76 may be adjustable or be otherwise made dynamically variable.For example, the range of the obstacle sensors 76 may be extended ifcertain operating conditions are detected, etc. As an example, the rangeof the obstacle sensors 76 may be adjusted based upon the speed of thetruck 10 when advancing under wireless remote control.

Algorithm

According to various aspects of the present invention, a steercorrection algorithm is implemented, e.g., by the controller 103.Referring to FIG. 11, a steer correction algorithm comprises determiningwhether a steer bumper zone warning is detected at 152. A steer bumpersignal warning at 152 may comprise, for example, detecting the presenceof an object within first and/or second steer bumper zones 132A, 132Bwith a laser sensor 200, such as a model number LMS 100 or LMS 111 lasersensor manufactured by Sick AG located in Waldkirch, Germany. The lasersensor 200 may be mounted to the power unit 14, see FIG. 12. The firststeer bumper zone 132A may also be designated as a left steer bumperzone and the second steer bumper zone 132B may also be designated as aright steer bumper zone, see FIG. 12. If a steer bumper zone warning isreceived, a determination is made at 154 whether the steer bumper zonewarning indicates that an object is detected to the left or to the rightof the truck 10, e.g., whether the detected object is in the first steerbumper zone 132A or the second steer bumper zone 132B. For example, thelaser sensor 200 may generate two outputs, a first output signaldesignating whether an object is detected in the first (left) steerbumper zone 132A, and a second signal designating whether an object isdetected in the second (right) steer bumper zone 132B. Alternatively,the controller 103 may receive raw laser sensor data andprocess/distinguish the first and second steer bumper zones 132A, 132Busing a predetermined mapping.

For example, referring additionally to FIG. 12, the laser sensor 200 maysweep a laser beam in an area in front of truck 10. In this regard,multiple laser sensors may be utilized, or one or more laser beams maybe swept, e.g., to raster scan one or more areas forward of the truck10. If an object is present in an area where the laser beams are swept,the object reflects the beam back to the laser sensor 200, which iscapable of generating object location data from which the location ofthe sensed object can be determined either by the sensor 200 or thecontroller 103, as is known in the laser sensor art. In this regard, thelaser sensor 200 may independently define and scan the left and rightsteer bumper zones, or the controller 103 may derive the left and/orright steer bumper zones based upon the raster scan of the laser(s).Still further, alternate scanning patterns may be utilized, so long asthe controller 103 can determine whether a detected obstacle is to theleft or to the right of the truck 10.

As a few additional examples, although a laser sensor 200 is illustratedfor purposes of discussion herein, other sensing technologies may beutilized, examples of which may include ultrasonic sensors, infraredsensors, etc. For example, ultrasonic sensors, e.g., located to thesides of the truck 10, may define the left and right steer bumper zones132A, 132B. Selection of the type(s) of sensors used on the truck 10 maydepend upon the particular operating conditions of the truck 10.

Additionally, the laser sensor 200 or one or more additional sensors maybe used to define other detection zones, e.g., for stopping, speedlimiting, etc. The laser sensor 200 (or one or more additional sensors)may define a “stop zone”, and/or a “slow down zone” as described indetail herein. For example, if a single stop zone is defined and anobject is detected in the stop zone, which may extend, for example,about 1.2 meters in front of a forward traveling direction of the truck10, the controller 103 may cause the truck 10 to stop, as set out indetail herein. Additionally or alternatively, if an object is detectedin a slow down zone, the controller 103 may cause the truck 10 to slowdown. It is noted that, according to this embodiment, it may bepreferable to define a stop zone while not defining a slow down zone.

Further, the truck 10 may comprise one or more load presence sensors 53,see FIG. 12. The load presence sensor(s) 53 may comprise proximity orcontact technology, e.g., a contact switch, a pressure sensor, anultrasonic sensor, optical recognition device, infrared sensor or othersuitable technology that detects the presence of a suitable loadcarrying structure 55, e.g., a pallet or other platform, collectioncage, etc. The controller 103 may refuse to implement a travel commandif one or more of the load presence sensors 53 indicate that the loadplatform 55 is not in a valid designated position. Still further, thecontroller 103 may communicate with the brake controller 108 to stop thetruck 10 if the load presence sensors 53 detect a change of the loadplatform 55 from a valid designated position.

It should be understood that any number of detection zones may beimplemented, and the implemented detection zones may overlap or definediscrete, mutually exclusive zones. Depending upon the sensor and sensorprocessing technologies utilized, the input(s) to the controller 103designating an object in the steer bumper zones 132A, 132B may be inother formats. As yet a further illustration, the first and second lasersteer bumper zones 132A, 132B may be defined by both ultrasonic sensorsand one or more laser sensors. For example, the laser sensor 200 may beutilized as a redundant check to verify that the ultrasonic sensorsproperly detect an object in either the left or right steer bumper zones132A, 132B, or vice versa. As yet a further example, ultrasonic sensorsmay be utilized to detect an object in the left or right steer bumperzones 132A, 132B and the laser sensor 200 may be utilized to distinguishor otherwise locate the object to determine whether the object wasdetected in the left steer bumper zone 132A or the right steer bumperzone 132B. Other arrangements and configurations may alternatively beimplemented.

If a steer bumper zone warning designates that an object is detected inthe left steer bumper zone 132A, then a steer correction routine isimplemented at 156 that includes computing a steer angle correction tosteer the truck 10 to the right according to a first set of parameters.By way of illustration and not by way of limitation, a steer rightcorrection implemented at 156 may include steering the truck 10 to theright at a right direction steer angle. In this regard, the rightdirection steer angle may be fixed or variable. For example, thecontroller 103 may command the steer controller 112 to ramp up to somedesired steer angle, e.g., 8-10 degrees to the right. By ramping up to afixed steer angle, sudden changes in the angle of the steer wheel(s)will not occur, resulting in a smoother performance. The algorithmaccumulates the distance traveled at the steer correction angle, whichmay be a function of how long the appropriate steer bumper input isengaged.

According to various aspects of the present invention, the steered wheelangular change may be controlled to achieve, for example, asubstantially fixed truck angle correction as a function of accumulatedtravel distance. The travel distance accumulated while performing asteer correction maneuver may be determined based upon any number ofparameters. For example, the distance traveled during the steercorrection may comprise the distance traveled by the truck 10 until thedetected object is no longer within the associated left bumper detectionzone 132A. The accumulated travel distance may also/alternativelycomprise, for example, traveling until a time out is encountered,another object is detected in any one of the bumper or detection zones,and/or predetermined maximum steer angle is exceeded, etc.

Upon exiting a right steer correction at 156, e.g., by maneuvering thetruck 10 so that no object is detected within the left steer bumperdetection zone 132A, a left steer compensation maneuver is implementedat 158. The left steer compensation maneuver at 158 may comprise, forexample, implementing a counter steer to adjust the travel direction ofthe truck 10 to an appropriate heading. For example, the left steercompensation maneuver may comprise steering the truck 10 at a selectedor otherwise determined angle for a distance that is a percentage of thepreviously accumulated travel distance. The left steer angle utilizedfor the left steer compensation maneuver may be fixed or variable, andmay be the same as, or different from the steer angle utilized toimplement the right steer correction at 156.

By way of illustration and not by way of limitation, the distanceutilized for the left steer compensation maneuver at 158 may beapproximately one quarter to one half of the accumulated travel distancewhile implementing the right steer correction at 156. Similarly, theleft steer angle to implement the left steer compensation maneuver maybe approximately one half of the angle utilized to implement the rightsteer correction at 156. Thus, assume that the right steer angle is 8degrees and the accumulated steer correction travel distance is 1 meter.In this example, the left steer compensation may be approximately onehalf of right steer correction, or −4 degrees, and the left steercompensation will occur for a travel distance of approximately ¼ metersto ½ meters.

The particular distance and/or angle associated with the left steercompensation maneuver at 158 may be selected, for example, so as toclampen the “bounce” of the truck 10 as the truck 10 moves along itscourse to steer correct away from detected obstacles. As anillustration, if the truck 10 steer corrects at a fixed degrees perdistance traveled, the controller 103 may be able to determine how muchthe corresponding truck angle has changed, and therefore, adjust theleft steer compensation maneuver at 158 to correct back towards theoriginal or other suitable heading. Thus, the truck 10 will avoid “pingponging” down an aisle and instead, converge to a substantially straightheading down the center of the aisle without tedious manualrepositioning required by the truck operator. Moreover, the left steercompensation maneuver at 158 may vary depending upon the particularparameters utilized to implement the right steer correction at 156.

Correspondingly, if a steer bumper zone warning designates that anobject is detected in the right steer bumper zone 132B, then a steercorrection routine is implemented at 160 that includes computing a steerangle correction to steer the truck 10 to the left according to a secondset of parameters. By way of illustration and not by way of limitation,a steer left correction implemented at 160 may include steering thetruck 10 to the left at a left steer angle. In this regard, the leftsteer correction maneuver at 160 may be implemented in a manneranalogous to that described above at 156, except that the correction isto the right at 156 and to the left at 160.

Similarly, upon exiting a left steer correction at 160, e.g., bymaneuvering the truck 10 so that no object is detected within the rightbumper detection zone 132B, a right steer compensation maneuver isimplemented at 162. The right steer compensation maneuver at 162 maycomprise, for example, implementing a counter steer to adjust the traveldirection of the truck 10 to an appropriate heading in a manneranalogous to that described at 158, except that the steer compensationmaneuver at 158 is to the left and the steer compensation maneuver at162 is to the right.

After implementing the steer compensation maneuver at 158 or 162, thetruck may return to a substantially straight heading, e.g., 0 degrees at164 and the process loops back to the beginning to wait for thedetection of another object in either of the steer bumper zones 132A,132B.

The algorithm can further be modified to follow various control logicimplementations and/or state machines to facilitate various anticipatedcircumstances. For example, it is possible that a second object willmove into either steer bumper zone 132A or 132B while in the process ofimplementing a steer compensation maneuver. In this regard, the truck 10may iteratively attempt to steer correct around the second object. Asanother illustrative example, if object(s) are simultaneously detectedin both the left and right steer bumper zones 132A, 132B, the controller103 may be programmed to maintain the truck 10 at its current heading(e.g., zero degree steer angle), until either one or more steer bumperzones 132A, 132B are cleared or the associated detection zones cause thetruck 10 to come to a stop.

According to further aspects of the present invention, a user and/orservice representative may be able to customize the response of thesteer angle correction algorithm parameters. For example, a servicerepresentative may have access to programming tools to load customizedvariables, e.g., in the controller 103, for implementing steercorrection. As an alternative, a truck operator may have controls thatallow the operator to input customized parameters into the controller,e.g., via potentiometers, encoders, a software user interface, etc.

The output of the algorithm illustrated in FIG. 11 may comprise, forexample, an output that defines a steer correction value that may becoupled from the controller 103 to an appropriate control mechanism ofthe truck 10. For example, the steer correction value may comprise a +/−steer correction value, e.g., corresponding to steer left or steerright, that is coupled to a vehicle control module, steer controller112, e.g., as illustrated in FIG. 2, or other suitable controller. Stillfurther, additional parameters that may be editable, e.g., to adjustoperational feel may comprise the steer correction angle, a steercorrection angle ramp rate, a bumper detection zone size/range for eachsteer bumper zone, truck speed while steer correcting, etc.

Referring to FIG. 12, assume in the illustrative example, that the truck10 is traveling in response to receiving a remote wireless travelrequest and that before the truck 10 can travel a predetermined jogdistance, the truck 10 travels into a position where a rack leg 172 anda corresponding pallet 174 are in the path of the left steer bumper zone132A. Keeping with the exemplary algorithm of FIG. 11, the truck 10,e.g., via the controller 103, may implement an obstacle avoidancemaneuver by entering a steer correction algorithm, to steer the truck tothe right. For example, the controller 103 may compute or otherwiselookup or retrieve a steer correction angle that is communicated to asteer controller 112 to turn the drive wheel(s) of the truck 10.

The truck 10 maintains steer correction until an event occurs, such asthe disengagement of the object, e.g., when the scanning laser or otherimplemented sensor technology no longer detects an object in the leftsteer bumper zone 132. Assume that the truck 10 accumulated a traveldistance of one half of a meter during the steer correction maneuver,which was fixed at 8 degrees. Upon detecting that the left steer bumperzone signal has disengaged, a counter steer compensation is implementedto compensate for the change in heading caused by the steer correction.By way of example the steer compensation may steer the truck 10 to theleft for approximately one quarter meter accumulated travel distance, at4 degrees. For very narrow aisles, the Left/Right steer bumper zonesensors may provide very frequent inputs/little time between sensescompared to relatively wider aisles.

The various steer angle corrections and corresponding counter steercompensations may be determined empirically, or the angles, ramp rates,accumulated distances, etc., may be computed, modeled or otherwisederived.

In the illustrative arrangement, the system will try to maintain thetruck 10 centered in the aisle as the truck 10 advances in response toreceiving a corresponding wirelessly transmitted travel request by thetransmitter 70. Moreover, bounce, e.g., as measured by the distance fromthe centerline of a warehouse aisle, is clamped. Still further, theremay be certain conditions where the truck 10 may still require someoperator intervention in order to maneuver around certain objects in theline of travel.

The description of the present invention has been presented for purposesof illustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention.

Having thus described the invention of the present application in detailand by reference to embodiments thereof, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims.

What is claimed is:
 1. A method for operating a materials handlingvehicle utilizing multiple detection zones comprising: defining a firstdetection zone in an area proximate to the vehicle; defining a seconddetection zone in an area proximate to the vehicle; performing a firstaction if an unacceptable detection occurs in the first detection zone;and performing a second action different from the first action if anunacceptable detection occurs in the second detection zone.
 2. Themethod of claim 1, wherein the first and second detection zones aredefined by at least one contactless obstacle sensor on the vehicle. 3.The method of claim 1, wherein: said defining a first detection zonecomprises defining a stop zone; said defining a second detection zonecomprises defining a first speed zone; said performing a first actioncomprises implementing a stop action to stop the vehicle if the vehicleis traveling and an obstacle is detected in the stop zone; and saidperforming a second action comprises implementing a speed reductionaction to reduce the speed of the vehicle to a first predetermined speedif the vehicle is traveling at a speed greater than the firstpredetermined speed and an obstacle is detected in the first speed zone.4. The method of claim 3, further comprising: defining a third detectionzone in an area at least partially in front of the forward travelingdirection of the vehicle, the third detection zone comprising a secondspeed zone; and implementing a second speed reduction action to reducethe speed of the vehicle to a second predetermined speed if the vehicleis traveling at a speed greater than the second predetermined speed andan obstacle is detected in the second speed zone.
 5. The method of claim3, further comprising preventing operation of the vehicle if an obstacleis detected within the stop zone before the vehicle begins travel. 6.The method of claim 1, further comprising: associating each detectionzone with an associated speed control zone and a corresponding maximumspeed; and limiting the vehicle speed to the predetermined maximum speedof an associated speed control zone based upon the detection of anobstacle in that speed zone.
 7. The method of claim 1, furthercomprising modifying at least one vehicle parameter other than speed inresponse to detecting an obstacle in at least one detection zone.
 8. Themethod of claim 1, wherein at least one of the detection zones comprisesa steer angle correction zone, and further comprising implementing asteer angle correction if an obstacle is detected in a correspondingsteer angle correction zone.
 9. The method of claim 8, wherein saidimplementing a steer angle correction if an obstacle is detected in acorresponding steer angle correction zone further comprises selecting adirection of steer angle adjustment based upon a determination of aposition of a detected obstacle.
 10. The method of claim 8, wherein theat least two detection zones comprise a plurality different steer anglecorrection zones, and further comprising implementing a different steerangle correction amount for each steer angle correction zone.
 11. Themethod of claim 1, further comprising remotely controlling the vehiclevia a receiver at the vehicle for receiving transmissions from acorresponding remote control device, the transmissions comprising atleast a first type signal designating a travel request requesting thevehicle to travel.
 12. The method of claim 1, wherein said performing afirst action comprises performing a first action if an obstacle isdetected in the first detection zone.
 13. The method of claim 12,wherein said performing a second action comprises performing a secondaction different from the first action if a load platform on the vehicleis not in a valid designated position.